Class: Datadog::OpenTracer::Tracer

Inherits:
OpenTracing::Tracer
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/ddtrace/opentracer/tracer.rb

Overview

OpenTracing adapter for Datadog::Tracer

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Tracer

Returns a new instance of Tracer.


16
17
18
19
# File 'lib/ddtrace/opentracer/tracer.rb', line 16

def initialize(options = {})
  super()
  @datadog_tracer = Datadog::Tracer.new(options)
end

Instance Attribute Details

#datadog_tracerObject (readonly)

Returns the value of attribute datadog_tracer


9
10
11
# File 'lib/ddtrace/opentracer/tracer.rb', line 9

def datadog_tracer
  @datadog_tracer
end

Instance Method Details

#extract(format, carrier) ⇒ SpanContext?

Extract a SpanContext in the given format from the given carrier.

Parameters:

  • format (OpenTracing::FORMAT_TEXT_MAP, OpenTracing::FORMAT_BINARY, OpenTracing::FORMAT_RACK)
  • carrier (Carrier)

    A carrier object of the type dictated by the specified `format`

Returns:

  • (SpanContext, nil)

    the extracted SpanContext or nil if none could be found


180
181
182
183
184
185
186
187
188
189
190
191
192
# File 'lib/ddtrace/opentracer/tracer.rb', line 180

def extract(format, carrier)
  case format
  when OpenTracing::FORMAT_TEXT_MAP
    TextMapPropagator.extract(carrier)
  when OpenTracing::FORMAT_BINARY
    BinaryPropagator.extract(carrier)
  when OpenTracing::FORMAT_RACK
    RackPropagator.extract(carrier)
  else
    warn 'Unknown extract format'
    nil
  end
end

#inject(span_context, format, carrier) ⇒ Object

Inject a SpanContext into the given carrier

Parameters:

  • span_context (SpanContext)
  • format (OpenTracing::FORMAT_TEXT_MAP, OpenTracing::FORMAT_BINARY, OpenTracing::FORMAT_RACK)
  • carrier (Carrier)

    A carrier object of the type dictated by the specified `format`


162
163
164
165
166
167
168
169
170
171
172
173
# File 'lib/ddtrace/opentracer/tracer.rb', line 162

def inject(span_context, format, carrier)
  case format
  when OpenTracing::FORMAT_TEXT_MAP
    TextMapPropagator.inject(span_context, carrier)
  when OpenTracing::FORMAT_BINARY
    BinaryPropagator.inject(span_context, carrier)
  when OpenTracing::FORMAT_RACK
    RackPropagator.inject(span_context, carrier)
  else
    warn 'Unknown inject format'
  end
end

#scope_managerScopeManager

Returns the current ScopeManager.

Returns:


22
23
24
# File 'lib/ddtrace/opentracer/tracer.rb', line 22

def scope_manager
  @scope_manager ||= ThreadLocalScopeManager.new
end

#start_active_span(operation_name, child_of: nil, references: nil, start_time: Time.now, tags: nil, ignore_active_scope: false, finish_on_close: true) {|Scope| ... } ⇒ Scope

Returns a newly started and activated Scope.

If the Tracer's ScopeManager#active is not nil, no explicit references are provided, and `ignore_active_scope` is false, then an inferred References#CHILD_OF reference is created to the ScopeManager#active's SpanContext when start_active is invoked.

If specified, the `references` parameter must be omitted.

Parameters:

  • operation_name (String)

    The operation name for the Span

  • child_of (SpanContext, Span) (defaults to: nil)

    SpanContext that acts as a parent to the newly-started Span. If a Span instance is provided, its context is automatically substituted. See [Reference] for more information.

  • references (Array<Reference>) (defaults to: nil)

    An array of reference objects that identify one or more parent SpanContexts.

  • start_time (Time) (defaults to: Time.now)

    When the Span started, if not now

  • tags (Hash) (defaults to: nil)

    Tags to assign to the Span at start time

  • ignore_active_scope (Boolean) (defaults to: false)

    whether to create an implicit References#CHILD_OF reference to the ScopeManager#active.

  • finish_on_close (Boolean) (defaults to: true)

    whether span should automatically be finished when Scope#close is called

Yields:

  • (Scope)

    If an optional block is passed to start_active it will yield the newly-started Scope. If `finish_on_close` is true then the Span will be finished automatically after the block is executed.

Returns:

  • (Scope)

    The newly-started and activated Scope


52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
# File 'lib/ddtrace/opentracer/tracer.rb', line 52

def start_active_span(operation_name,
                      child_of: nil,
                      references: nil,
                      start_time: Time.now,
                      tags: nil,
                      ignore_active_scope: false,
                      finish_on_close: true)

  # When meant to automatically determine the parent,
  # Use the active scope first, otherwise fall back to any
  # context generated by Datadog, so as to append to it and gain
  # the benefit of any out-of-the-box tracing from Datadog preceding
  # the OpenTracer::Tracer.
  #
  # We do this here instead of in #start_span because #start_span generates
  # spans that are not assigned to a scope, a.k.a not supposed to be used by
  # subsequent spans implicitly. By using the existing Datadog context, the span
  # effectively ends up "assigned to a scope", by virtue of being added to the
  # Context. Hence, it would behave more like an active span, which is why it
  # should only be here.
  unless child_of || ignore_active_scope
    child_of = if scope_manager.active
                 scope_manager.active.span.context
               else
                 SpanContextFactory.build(datadog_context: datadog_tracer.call_context)
               end
  end

  # Create the span, and auto-add it to the Datadog context.
  span = start_span(
    operation_name,
    child_of: child_of,
    references: references,
    start_time: start_time,
    tags: tags,
    ignore_active_scope: ignore_active_scope
  )

  # Overwrite the tracer context with the OpenTracing managed context.
  # This is mostly for the benefit of any out-of-the-box tracing from Datadog,
  # such that spans generated by that tracing will be attached to the OpenTracer
  # parent span.
  datadog_tracer.provider.context = span.datadog_span.context

  scope_manager.activate(span, finish_on_close: finish_on_close).tap do |scope|
    if block_given?
      begin
        yield(scope)
      ensure
        scope.close
      end
    end
  end
end

#start_span(operation_name, child_of: nil, references: nil, start_time: Time.now, tags: nil, ignore_active_scope: false) ⇒ Span

Like #start_active_span, but the returned Span has not been registered via the ScopeManager.

If specified, the `references` parameter must be omitted.

Parameters:

  • operation_name (String)

    The operation name for the Span

  • child_of (SpanContext, Span) (defaults to: nil)

    SpanContext that acts as a parent to the newly-started Span. If a Span instance is provided, its context is automatically substituted. See [Reference] for more information.

  • references (Array<Reference>) (defaults to: nil)

    An array of reference objects that identify one or more parent SpanContexts.

  • start_time (Time) (defaults to: Time.now)

    When the Span started, if not now

  • tags (Hash) (defaults to: nil)

    Tags to assign to the Span at start time

  • ignore_active_scope (Boolean) (defaults to: false)

    whether to create an implicit References#CHILD_OF reference to the ScopeManager#active.

Returns:

  • (Span)

    the newly-started Span instance, which has not been automatically registered via the ScopeManager


125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
# File 'lib/ddtrace/opentracer/tracer.rb', line 125

def start_span(operation_name,
               child_of: nil,
               references: nil,
               start_time: Time.now,
               tags: nil,
               ignore_active_scope: false)

  # Derive the OpenTracer::SpanContext to inherit from.
  parent_span_context = inherited_span_context(child_of, ignore_active_scope: ignore_active_scope)

  # Retrieve Datadog::Context from parent SpanContext.
  datadog_context = parent_span_context.nil? ? nil : parent_span_context.datadog_context

  # Build the new Datadog span
  datadog_span = datadog_tracer.start_span(
    operation_name,
    child_of: datadog_context,
    start_time: start_time,
    tags: tags || {}
  )

  # Build or extend the OpenTracer::SpanContext
  span_context = if parent_span_context
                   SpanContextFactory.clone(span_context: parent_span_context)
                 else
                   SpanContextFactory.build(datadog_context: datadog_span.context)
                 end

  # Wrap the Datadog span and OpenTracer::Span context in a OpenTracer::Span
  Span.new(datadog_span: datadog_span, span_context: span_context)
end